Determination of lead in human placenta tissue employing slurry sampling and detection by electrothermal atomic...

A new analytical procedure was developed for the determination of lead in human placental tissue by direct ultrasonic slurry sampling combined with electrothermal atomic absorption spectrometry (SS-ET AAS). Samples of dried and crushed placental tissue were mixed with 10 mL of 0.20% (v/v) HNO₃ and homogenised. The slurries were then transferred to autosampler cups where they were sonicated using an ultrasonic probe prior to injection into a graphite tube with an L'vov platform. The effects of several chemical modifiers, including Mg(NO₃)₂, Pd(NO₃)₂, and NH₄H₂PO₄, were investigated for the stabilisation of lead during thermal pre-treatment. Lead in the slurries was effectively stabilised up to 1200 °C with the Pd(NO₃)₂ modifier providing the best results with complete atomisation at 1900 °C. H₂O₂ was used as a chemical modifier; dilute HNO₃ and HCl were examined as slurry media. The limit of detection and the limit of quantification for lead obtained under optimised conditions were 0.17 μg g^-1 and 0.56 μg g^-1, respectively. The relative standard deviation estimated from twenty replicate measurements of spike solution at a concentration of 50.00 μg L^-1 for lead was 1.51%. The accuracy of the method was confirmed by analysis of the standard reference material BCR 185R "Bovine Liver". The proposed technique is simple, sensitive and environmentally friendly, and the risk of contamination is low. The method was applied to lead determination in real samples of human placental tissue. The 14 samples were taken just after delivery at the Gynaecology and Obstetrics Department of the Faculty Hospital with Outpatients Clinic in Bratislava over the course of 2019.